1. Field of the Invention
The prevent invention relates to a magnetic disk apparatus usable for, for example, a memory device in a computer.
2. Description of the Related Art
Magnetic disk apparatuses generally use a non-contact magnetic head in order to avoid damaging a magnetic disk acting as a recording medium. Usually, a magnetic head mounted on a floating slider is used. The slider is attached to, for example, a flexible flexure member, which in attached to a load beam provided on a head actuator arm.
While the magnetic disk apparatus is in an operation mode, the slider floats above the magnetic disk at a microscopic floating distance by the balance between the pressing force of the load beam for biasing the slider onto a surface of the magnetic disk and the floating force caused by the air flow which in generated by the rotation of the magnetic disk. In such a magnetic disk apparatus, a contact start stop (CSS) system is used, according to which the magnetic disk apparatus starts and stops while the magnetic disk and the magnetic head are in contact with each other. In this specification, the term xe2x80x9cfloating distancexe2x80x9d is defined as the vertical distance between the slider floating above the magnetic disk and the surface of the magnetic disk.
According to the CSS system, the magnetic head is always in a wait state while being in contact with a surface of the magnetic disk when the magnetic disk apparatus to in a stop mode, i.e., is not operated. When the magnetic disk apparatus is started, the magnetic disk rotates, and the magnetic head is lifted up from the surface of the magnetic disk by the air flow generated by the rotation of the magnetic disk. Then, the magnetic head is driven to access an appropriate location of the magnetic disk, and thus information is recorded on or reproduced from the magnetic disk. When the magnetic disk apparatus is stopped, the magnetic head arrives on the surface of the magnetic disk and held in contact with the surface of the magnetic disk.
The CSS system has a problem in that since the magnetic head is lifted up from and arrives on the surface of the magnetic disk, the magnetic head and the magnetic disk may undesirably be damaged by the impact of contact between the magnetic head and the magnetic disk.
The CSS system has another problem in that after the magnetic head and the magnetic disk are in contact with each other for an extended period of time, the magnetic head and the magnetic disk are adsorbed to each other end cannot be separated from each other even when the magnetic disk apparatus is started.
Japanese Laid-Open Publication No. 60-38773 proposes that the magnetic head is out of contact with the magnetic disk while the magnetic disk apparatus is in a atop mode, so that the magnetic head and the magnetic disk are prevented from being adsorbed to each other.
FIG. 20 is an isometric view illustrating a structure of a slider holding section 200 for holding a slider 100 of a conventional magnetic disk apparatus. As shown in FIG. 20, the slider 100 provided with a magnetic head mounted thereon is secured by adhesion on a bottom surface of a flexible flexure member 101. The flexure member 101 is secured to a bottom surface of a load beam 104.
The load beam 104 is provided for applying a prescribed pressing load generated in a leaf spring section 104A of the load beam 104 to the slider 100. The load beam 104 is secured to a tip of a head actuator arm 102 via a base plate 103. The head actuator arm 102 is rotated about a support an a base substrate (not shown).
FIG. 21 shows an enlarged isometric view of the load beam 104, the flexure member 101 and the slider 100 of the slider holding section 200.
As shown in FIG. 21, the pressing load is applied to the slider 100 by the load beam 104 through a projection 104B of the load beam 104. The flexure member 101 is maintained flexible in rolling directions RR and in Ditch directions PP. In this specification, the term xe2x80x9crolling directionxe2x80x9d is defined to refer to the direction perpendicular to the longitudinal direction of the head actuator arm.
An shown above, the flexure member 101 for holding the slider 100 is attached to the load beam 104.
FIG. 22 is a cross-sectional view of FIG. 21, illustrating the load beam 104, the flexure member 101, and the slider 100 of the slider holding section 200.
In the above-described conventional slider holding section 200 of the conventional magnetic disk apparatus, a separation arm (not shown) raises the load beam 100 by a contact friction so as to float the slider 100 which is attached to the tip of the load beam 104 via the flexure member 101. During this operation, the parallel relationship between the slider 100 and a magnetic disk 5 can undesirably be destroyed due to, for example, the frictional force between the separation arm and the load beam 104 and the dispersion in the position of the load beam 104 acted on by the separation arm. The reason is that the flexure member 101 for holding the slider 100 is attached to the load beam 104.
In the case where the above-mentioned parallel relationship is destroyed, the slider 100 undesirably contacts a surface 5S (FIGS. 5A and 5B) of the magnetic disk 5 to cause friction when the slider 100 is lifted up from the surface 5S.
During the magnetic disk apparatus is in an operation mode, the load beam 104 resonates due to the vibration of the magnetic disk apparatus caused by an external disturbance. Since the flexure member 101 is attached to the load beam 104, the flexure member 101 vibrates integrally with the load beam 104. As a result, the slider 100 attached to the flexure member 101 undesirably contacts the magnetic disk 5.
As described above, when the conventional magnetic disk apparatus is started or stopped, it is difficult to maintain the slider and the magnetic, disk substantially parallel to each other and to maintain the floating distance. Accordingly, the slider and the magnetic disk are damaged, resulting in that information is prevented from correctly recorded on or reproduced from the magnetic disk.
According to one aspect of the invention, a magnetic disk apparatus includes a slider for holding a magnetic head for scanning a magnetic disk and performing recording and reproduction of information; a flexure member for holding the slider, the flexure member having an elasticity in a direction substantially perpendicular to a surface of the magnetic disks a head actuator arm for holding the flexure member and causing the magnetic head to scan the magnetic disk; and an elastic body provided on the head actuator arm for applying a load for pressing the slider toward the surface of the magnetic disk.
In one embodiment of the invention, the elastic body includes a leaf spring, and the leaf spring has a cantilever structure.
In one embodiment of the invention, the magnetic disk apparatus further includes unloading means for releasing the slider from the load.
In one embodiment of the invention, the unloading means releases the slider from the load when the slider is positioned above an outermost track of the magnetic disk.
In one embodiment of the invention, the unloading means includes a ramp slidably contactable with the elastic body so as to raise the elastic body from the flexure member.
In one embodiment of the invention, the elastic body includes an engaging section slidably contactable with the ramp.
In one embodiment of the invention, the unloading means includes a shape-memory alloy member provided on the elastic body for banding the elastic body so am to release the slider from the load.
In one embodiment of the invention, the unloading means includes a thin film piezoelectric member provided on the elastic body for banding the elastic body so as to release the slider tram the load.
In one embodiment of the invention, the unloading means includes an unloading arm secured to the head actuator arm; and a ramp slidably contactable with the uploading arm so as to allow the unloading arm to release the slider from the load. The unloading arm releases the slider from the load so as to allow the slider top be maintained substantially parallel to the surface of the magnetic disk.
In one embodiment of the invention, the unloading arm is engageable with the elastic body so as to release the slider from the load.
In one embodiment of the invention, the unloading arm has one end secured to the head actuator arm, another end slidably contactable with the ramp in an area including an unloading position and the vicinity thereof, and a central portion engageable with the elastic body so as to release the slider from the load.
In one embodiment of the invention, the ramp includes a guide having an inclined surface which is slidably contactable with the unloading arm, and the inclined surface is inclined toward a central portion of the magnetic disk.
In one embodiment of the invention, the unloading arm includes a leaf spring, and the leaf spring has a cantilever structure.
In one embodiment of the invention, the ramp is located so as to avoid overlapping the surface of the magnetic disk.
In one embodiment of the invention, the unloading arm la substantially parallel to a longitudinal direction of the head actuator arm.
In one embodiment of the invention, the unloading arm is located on a side of the elastic body opposite from the magnetic disk.
In one embodiment of the invention, the elastic body has an engaging section which is engageable with the unloading are so as to release the slider from the load.
In one embodiment of the invention, the elastic body is provided with a protrusion for pressing the flexure member with the load.
In one embodiment of the invention, the flexure member is provided with a protrusion for receiving the load.
According to another aspect of the invention, a magnetic disk apparatus includes a slider for holding a magnetic head for scanning a magnetic disk end performing recording and reproduction of information; a flexure member for holding the slider, the flexure member having an elasticity in a direction substantially perpendicular to a surface of the magnetic disk; a head actuator arm for holding the flexure member and causing the magnetic head to scan the magnetic disk; a motor for rotating the magnetic disk; and a controller for controlling a rotation speed of the motor. The slider has a recess in a surface thereof facing the surface of the magnetic disk. The recess is provided in a manner that a first air pressure generated by the rotation of the disk in a direction to cause the slider to approach the surface of the magnetic disk is larger than a second air pressure generated in a direction to cause the slider to be distanced from the surface of the magnetic disk. The controller increases the rotation speed of the motor to a level higher than a proscribed rotation speed and then decreases the rotation speed to the prescribed rotation speed.
Thus, the invention described herein makes possible the advantages of providing a magnetic disk apparatus for maintaining a slider and a magnetic disk substantially parallel with an appropriate floating distance therebetween so as to prevent damaging the slider and the magnetic disk, so that information la correctly recorded on or reproduced from the magnetic disk.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.